Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The particular size of wind turbine rotor blades is a significant factor contributing to the overall efficiency of the wind turbine. Specifically, increases in the length or span of a rotor blade may generally lead to an overall increase in the energy production of a wind turbine. Accordingly, efforts to increase the size of rotor blades aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source. However, as rotor blade sizes increase, so do the loads transferred through the blades to other components of the wind turbine (e.g., the wind turbine hub and other components). For example, longer rotor blades result in higher loads due to the increased mass of the blades as well as the increased aerodynamic loads acting along the span of the blade. Such increased loads can be particularly problematic in high-speed wind conditions, as the loads transferred through the rotor blades may exceed the load-bearing capabilities of other wind turbine components.
Certain surface features, such as spoilers, are known that may be utilized to separate the flow of air from the outer surface of a rotor blade, thereby reducing the lift generated by the blade and reducing the loads acting on the blade. However, these surface features are typically designed to be permanently disposed along the outer surface of the rotor blade. As such, the amount of lift generated by the rotor blade is reduced regardless of the conditions in which the wind turbine is operating. Thus, there is a need for a surface feature, such as an actuatable spoiler, that permits the loads acting on a rotor blade to be efficiently shed when desired (e.g., during high-speed wind conditions, such as wind gusts) without reducing the overall efficiency of the rotor blade during other operating conditions.
Additionally, various other surface features, such as vortex generators, are known that may be utilized to delay separation of the air flowing over a rotor blade, such as when the blade is oriented at a high angle of attack relative to the direction of the airflow. However, these surface features also produce drag on the rotor blade, thereby reducing the overall efficiency of the blade. Thus, there is a need for a surface feature, such as an actuatable vortex generator, that may be used to delay separation of the airflow from the rotor blade when needed (e.g., when the rotor blade is oriented at high angles of attack) without reducing the overall efficiency of the rotor blade when flow separation is not an issue.
Accordingly, a rotor blade having one or more actuatable surface features would be welcomed in the technology.